Method of refining mineral oils



June 20, 1939. E. TERRES ET AL 2,163,564

METHOD OF REFINING MINERAL OILS Filed May 23, 1955 2 Sheets-Sheet lASPHALTENES V MIX/N6 0ND SETTL/NG HSPHALT'F'EEE OIL DISSOLVED INFLUOEINE SOLVENT.

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June 20, 1939. E. TERRES ET AL 2,163,564

METHOD OF REFINING MINERAL OILS Filed May 23, 1935 2 Sheets-Sheet 2HZLMQHINE CGNJWININSWSOL VENT ASPHflLT/C WAX Y OIL STOCK HSPHALTENESM/X/NG AN D SETrL/NG ASPHALT- FEEE on.

DISSOL VED IN FLUOE/NE SOLVENTT CHILL/N6 FILTE WA X WAX-FREE OIL DIS8OLVED IN FLUOE/NE SOLVENT? HEATING SETTL/NG DISSOLVED SOLVE/VT PHASERECOVERY EAF'F/NATE l/NDISSOLl/ED SOLVENT FHA SE RECOVERY EXTRACT 3vwwwbo w ERNSTTZ-RRES, Ema/45,4 EGEBAETH;

(.JbSEPHMO-S, H /vs RHMSEB Patented June 20, 1939 STATES ATEN'E if.

METHOD OF REFINING MINERAL OILS Ernest Terres, New York, and ErichSaegebarth,

Long Island City, N. Y... and Joseph Moos, Berlin-Mariendorf,

and Hans Rainser, Berlin- Application May 23,

6 Claims.

Our invention relates to the refining of mineral oils by means ofsolvents and particularly relates to the use of organic and inorganicfluorine compounds in liquid state, which we have discovered to beparticularly advantageous for diiferent types of oil refining treatment.

We have found that liquid or liquefied fluorine compounds can be used assolvents or diluents for deasphaltizing and for dewaxing, in the mannerthat liquid propane is some times used. Also, that under certaincircumstances some of these compounds can likewise be used as selectivesolvents for solvent fractionation of oils, and that these compounds canbe used to good effect in conjunction with other solvents which areeither selective or non-selective with the fluorine com.- pounds or theoils to be treated.

The fluorine compounds can also be advantageously used in some cases asdiluents for oil to be acid treated, as by dissolving the oil in aliquid or liquefied fluorine compound and treating with sulfuric acid toremove unstable constituents of the oil. Various uses of the fluorinecompounds will be illustrated in subsequent examples.

The fluorine compounds which we consider as coming within the scope ofthis invention may be divided into three broad classes, namely:

(1) Aliphatic fluorine compounds, that is, fluorine derivatives ofaliphatic hydrocarbons having either straight or branched chains, orboth, including both saturated and unsaturated hydrocarbons, in whichone or more or all of the hydrogen atoms are substituted by fluorine,and

J which may also contain other substituted halogens such as chlorine andbromine. (2) Aromatic fluorine compounds. (3)Inorganic fluorinecompounds. Representative organic fluorine compounds coming within class(1) are as follows:

Pmafilne derioatives.-Mono-, di-, and tri-fluoromethane, and carbontetrafluoride. Monoto hexa-flucroethanes. Fluorine derivatives ofpropane, butane and higher parafiines. (The introduction of one or morefluorine atoms into propane may increase its specific qualities for oil1935, Serial No. 23,136

pentachloromonofluoroethane, symtetrachlorodi fluoroethane,trichlorotrifluoroethane, sym.dichlorotetrafluoroethane,unsym.dichlorotetrafluoroethane, monochloropentafluoroethane,unsyn1.tetrachlorodifluoroethane, unsym.tetrachlorodifluoroethane.Monofluorodibromotrichloroethane, difluorodibromodichloroethane,trifluorodibromomonochloroethane, tetrafluorodibromoethane,sym.difluorodibromodichloroethane. Also, corresponding derivatives ofpropane and butane.

Representatives of this class for which subsequent examples are givenare dichloromonofluoromethane, trichloromonofluoromethane,dichlorodifluoromethane and monobrornodifluoroethane.

Unsaturated aliphatic fluorine dcrivatioea-Dichlorodifiuoroethylene,monochlorotrifluoroethyl ene, trichloromono-fluoroethylene,tetrafluoroethylene, sym.dichlorodifluoroethylene and isomers thereof.

Representative aromatic fluorine compounds coming within class (2) areas follows:

Monofluorobenzol, difluorobenzol, fluorophenols, monofluoronaphthaleneand other fluorine and fluorine-halogen derivatives of benzol and itshomologues.

Representative inorganic fluorine compounds coming within class (3) areas follows:

Sulfur-containing compounds and other incrgam'ccompounds.Sulfuricoxyfluoride, sulfurousoxyfluoride, sulfurylfluoride,thionylfluoride, fluorosulflnic acid, fluorosulfonic acid, disulfur-(ii-fluoride, suliur-difluoride, sulfur-tetrafluoride, andsulfur-hexafluoride. Also corresponding compounds containing selenium ortellurium which do not react with oil.

Uther inorganic compounds.l luorine compounds of nitrogen, antimony,arsenic and tin, such as nitrogentrifluoride, antimony-pentaflm oride,arsenic-pentafluoride and arsenic-trifluoride. Also, compounds of boronsuch as the addition compound of hydrofluoric acid and metaboric acidhaving the formula: HBOzHzFz; and compounds of silicon which do notreact with oil.

The representatives of class (3) for which subsequent examples are givento indicate their ac ticn are sulfuric-oxyfluoride andsulfur-hexafluoride.

By the expression fluorine-halogen compounds or derivatives ashereinafter used is meant a compound which contains one or more of theother halogens, besides fluorine.

The foregoing fluorine compounds find application, according to ourinvention, in the following types of refining processes illustrated inthe accompanying diagrams:

(A) Deasphaltizing.

Some of the fluorine and fluorine-halogen de rivatives are suitable fordeasphaltizing insofar as they dissolve hydrocarbon oils entirely atproper temperatures, whereas asphaltenes are left undissolved. Byseparating the two layers and recovering the solvent from them, aresidual oil can be separated into asphaltines and deasphaltized oil.

(B) Dewaxing.

Some of the fluorine derivatives are suitable as dewaxing agents eitheralone or in combination with solvents which are soluble in the oil to bedewaxed as well as in the fluorine solvent, for example: benzol, toluol,methylchloride, ethylchloride, carbon bisulphide, ether, esters andothers.

(C) Selective solvent extraction.

Some of the mentioned fluorine derivatives may be used for solventextraction, in which case five different methods of applications may beemployed, namely:

(a) One of the mentioned fluorine or fluorinehalogen derivatives may beused alone or in mixtures with others.

(I?) The fluorine or fluorine-halogen derivatives mentioned under (03)may be used in mixture with one or more solvents of the class which ismiscible in any proportion with the hydrocarbon oil to be treated andwith the fluorine or fluorine-halogen selective solvent. Examples ofsuch solvents are given under the heading (B) dewaxing.

(c) The fluorine or fluorine-halogen derivatives mentioned under (a) maybe used in mixture with one or more solvents of the class which ismiscible in any proportion in the fluorine or fluorine-halogen selectivesolvent but which is not miscible or only to a small degree in thehydrocarbon oil to be treated.

Representatives of the latter group of auxiliary solvents are, forexample, water or alcohol. These auxiliary solvents serve to decreasethe solvent power of the fluorine or fluorine-halogen selective solvent,whereas the group of auxiliary solvents mentioned under (b) tend toincrease the solvent power of the selective solvent.

((1) The fluorine and fluorine-halogen compounds mentioned under (a) mayalso be used for solvent extraction in presence of another selectivesolvent with which they form two layers under proper conditions.Examples of combinations of solvents having this characteristic aregiven later.

We have disclosed under (A) above that some fluorine or fluorine-halogensolvents are capable of dissolving hydrocarbons entirely with theexception of asphaltenes. We have found that such fluorine orfluorine-halogen solvents may be used for extraction purposes incombination with a selective solvent which preferably dissolves theundesirable fractions of hydrocarbon oils but which at the same timeforms two layers with the fluorine or fluorine-halogen solvent.

(e) For the same purposes as mentioned under 1) we may also employ asolvent for refining purposes which is only selective with respect tothe fluorine and fluorine-halogen solvents but not with respect to thehydrocarbon oils, such as propane.

In the accompanying drawings, which show with the aid of explanatorylegends several modes of carrying out the invention for purposes ofillustration,

Fig. l is a flow diagram illustrating the use of our fluorinatedsolvents in the successive treatments of an asphaltic waxy oil stock forasphalt removal, wax removal and separation of the oil into a rafflnatefraction and an extract fraction by means of a selective solvent.

It will be understood, if theoil stock to be treated in accordance withthe method illustrated by the flow diagram Fig. 1 does not containasphalt but only wax, that the deasphaltizing step may be by-passed andthe solution of oil stock in the fluorine containing solvent may bedirectly introduced into the dewaxing apparatus, which is indicated inthe diagram by the chilling and filtering steps. Likewise, it will beunderstood, if the oil stock to be treated contains asphalt but no wax,that the dewaxing step may be by-passed and the deasphaltizedoil-solvent solution may be directly subjected to extraction with theselective solvent.

In. the extraction step, the deasphaltized and dewaxed solution of oilin fluorine containing solvent may be extracted with a selective solventalone; or it may be extracted with a mixture of the selective solventand the fluorine containing solvent, in which latter case part of thefluorine containing solvent flows directly from the supply to theextraction stage as shown in Fig. l, andjoins the selective solvent,prior to entering the mixing and settling step.

In the flow diagram Fig. 2, a method is illustrated in which anasphalting waxy oil stock is freed from asphalt and Wax by means of afluorinated solvent in the same manner as shown in Fig. 1; andthereafter, the oil solvent solution is heated until separation into twoliquid phases takes place, said phases consisting of a dissolved phase,or rafflnate phase, and an undissolved phase, or extract phase. Byrecovering the solvent from each of said phases the rafilnate and theextract are obtained, respectively.

It has been found that dichloromonofluoromethane andtrichloromonofluoromethane div solve mineral oil entirely attemperatures in the neighborhood of or above the pour point of oilswhich contain wax; also asphaltenes are dissolved entirely. Uponreducing the temperature of the solution containing the waxy lubricatingoil distillate dissolved in trichlorornonofluoromethane, the waxcrystallized out but a separation of two liquid phases is not obtainedat low temperatures.

In the following an example is given for the deWaXing of a Midcontinentoverhead cylinder: stock by means of trichlorornonofluoromethane.

Example 1 One volume of a Midcontinent overhead cylinder stock having10% wax, an A. P. I. gravity of 22.1, a S. U. viscosity of 154 at 210 F.and a pour point of F. was dissolved in 2 volumes oftrichloromonofluoromethane, cooled to -50 F. and passed through a filterat this temperature. After removal of the solvent from the filtrate anoil of 26 A. P. I. 182 S. U. viscosity at 219 F. and of a wax content ofzero, was obtained. The slack wax showed a melting point of F.

Dichloromonofluoromethane showed the same behavior as outlined forrichloromonofluoromethane.

In agitating dichloromonofiuoromethane with certain selective solvents,including chlorophenol, aniline, furfural, nitromethane, furfurylalcoholand others, it has been found that these selective solvents are entirelymiscible in dichlorornonofluoromethane and a phase separation does notoccur even at temperatures as low as 50 F,

Contrary to this experience trichlorornonorluoromethane gives a phaseseparation with aniline, nitromethane, furfural, furfurylalcohol andothers at low temperature, being only partially soluble therein, whereasit is entirely miscible with chlorophenol, quinoline, benzylalcohol,bromonaphthalene and others.

Dichloromonofiuoromethane and trichloromonofluoro methane can thereforebe used auxiliary solvent in combination with selective solvents withwhich they are entirely miscible. The presence ofdichlorornonofiuorometl'iane or trichloromonofluoromethane increases thesolvent power of the selective solvent and the treating result can becontrolled by the quantity of dichloromonofiuoromethane ortrichloromonofluoromethane used.

Trichloromonofiuoromethane may also be used in combination with aniline,nitromethane, i"rfural or furfurylalcohol, in which case the largestamount of trichloromonofluoromethane will serve as diluent and solventfor the rafilnate phase, whereas the extract phase will contain theselective solvent and the oil extract both saturated with the auxiliarysolvent trichloromcnofluoromethane,

The action of dichlorodifiuoromethane is quite different from thebehavior of trichloromonofiuoromethane or dichloromonofluoromethane inso far as it has no solubility for asphaltenes and its insolubility inselective solvents is more pronounced.

Residual oils may be freed from ashpaltenes by extraction by means ofdichlorodifluoromethane. The non-asphaltenic hydrocarbons are dissolvedentirely, whereas the asphaltenes form a separate layer and may besegregated in the normal way. This is shown in more detail in thefollowing example.

Example 2 Yield percent 8'? API degrees 21.9 Viscosity at 130 F 664iViscosity at 210 F 109 Carbon residue 3.0

The yield of asphalt amounted to 13% by volume.

Dichlorodifluoromethane is also suitable for dewaxing purposes, Thedeasphaltizing and dewaxin processes may also be combined. In such aresidual oil, for example, may be treated with the solvent in theneighborhood of 130 F. and t. e asphalt-free solution then cooled to thedewaxing temperature and fitered. If desired, may be the case with oilscontaining only small quanti 'es of asphaltenes, the separation of oiland wax even be carried out in one operation by d1ssolving the stock inthe solvent and cooling it to the dewaxing temperature and filtering it,in

which case the asphaltenes will be separated with the wax.

In. treating mineral oils with dichlorodifluoromethane it is necessaryto consider that the temperature range of entire miscibility is limitedbecause this solvent shows a negative temperature coefiicient in regardto the solubility of mineral oils. Upon heating the solution ofasphalt-free oil in the solvent, a point can be reached at whichseparation into two liquid phases occurs. One of the two phases containsthe bulk amount or" solvent, having a certain amount of oil in solution.This amount of oil is the smaller, the higher the temperature. The otherphase contains the unissolved and separated oil which is, of course,saturated with the solvent. Such phase separation will occur with aheavy cylinder stock at about 212 F. The specific gravity ofdichlorodifiuoromethane, which is 1.5 at -36 decreases to 0.83 at 225 F.The position of the two layers may therefore be reversed, depending uponthe temperature of the operation and the gravity of the oil.

Example 3 Undissclved Dissolved oil oil Yield, volume "percent" 89. 410. 6 A. P. I .degrees 23.6 27. 3 Viscosity at 130 F 1790 Viscosity at210 F 255 Carbon residue 4.1 1. 2

Dichlorodifluoromethane is not entirely miscible with certain selectivesolvents, such as quinoline, aniline, dichloroethylether, cresol,phenol, chlorophenol and others. It is therefore possible to use it incombination with the above mentioned solvents in the same manner thatpropane is used. This procedure is especially advantageous for thetreatment of residual oils and is likewise applicable to distillates, asshown by the following examples.

Example 4 One volume of a Midcontinent residual cylinder stock, withproperties as shown in the table of the next example, was agitated withfour volumes of dichlorodifluoromethane and one vol- Lune of phenol at104 F. The layers were allowed to settle afterwards and were separated.

The rafiinate layer was treated again with one volume of phenol at thesame temperature of 104 F. The layers were again separated and thesolvent was removed from the final rafdnate and from the combinedextract phases. The properties of the rafinate are shown in the table ofthe next example.

Example 5 One volume of the same hfidcontinent stock referred to in thepreceding example was agitated with. four volumes ofdichlorodifluoromethane and one volume of parachlorophenol at le0 F.Upon separation of the layers, the rafiinate phase was treated againwith one volume parachlorophenol at 149 13. Upon removal of the solventsfrom the final rafiinate and the com bined extract phases, the refinedoil was ob tained and the properties are shown in the following table:

Original Raflinate, ltafllnai e.

oil Example 4 Example 5 Yield, volume perccnt 1.00 51 A. P. I .dcgrees20 24. 5 27.5

Visc ity at 130 .l. .797 524 320 Viscosity at 210 F"... 145 98 77 Carbonresidue 5. 6 0. 67

Example 5 A dewaxed Midcontinent oil distillate was treated with 3volumes of dichlorodifiuorometln ane and 1 volume of aniline at 104 F.The layers were allowed to separate and were then i'reed of thesesolvents. The refined oil was contacted with 16% diatomaceous earth orother filter aid at 450 F. The properties of the finished raffinate areshown in the table the next example.

Example 7 ihe same dewaxed Midcontinent lubricating oi}. distillate wasextracted with 2 volumes of dichlorodifiuoromethane and two volumes ofparachlorophenol at 113 F. The phases were separated again and thesolvents were recovered by distillation. The specifications of therefined oil are shown in the following table:

given in Untreated Rafiinate, Railinate,

stock Example 6 Exampl 7 Yield volume perceut. 100 70 A. P. I d( grees v23. 2 24. 9 27. 5 Viscosity at F 1287 i 735 Viscosity at 210 F. 91 84. 57-1. 8 V. I 75 84 94 Carbon residue 1.9 l. l 0. 42

an equal volume of sulfuricoxyfluoride at room temperature, A separationinto two phases occurred.

Example 1'0 A Midcontinent residual oil upon agitation with an equalvolume of suliuricoxyfluoride at 87 F. showed a separation into twolayers.

Example 11 Equal volumes of chlorphenol and sulfuricoxyfluoride werebrought in contact at room temperature and cooled to 32 F. Separationtook place at this temperature, whereas above 32 F. chlorophenol wasentirely dissolved in sulfuricoxyfiuoride.

Our study of the four fluorine compounds, namely:

Dichloromonofiuoromethane TrichloromonofluoromethaneDichlorodifluoromethane (known as Freon) Sulfuricoxyfiuoride shows adifferent action of the respective fluorine compounds depending upon theother atoms present in the molecule. Whereas methane, ethane, propane,and other low boiling paraffines, are selective against mineral oils atproper temperatures and against asphaltenes, this behavior is changed bythe introduction of chlorine or bromine into the molecule. As known,methylchloride, carbontetrachloride or tribromomethane dissolve mineraloils and asphaltenes entirely. However, the introduction of fluorineinto a chlorinated paraffine seems to restore the selectivity, as shownby dichlorodifiuoromethane, and others includingmonochlorotr-ifiuoroethane, dichlorotrifiuoroethane,dichlorodifluoroethane, dichlorotetrafluoroethane,monochlorotrifiuoromethane, monobromodifiuoroethane, andmonochlorodifiuorethane.

Monofiuorine derivatives of chlorinated paraffiines, such asdichloromonofluoromethane and trichloromonofiuoromethane, do not possessthe selectivity of dichlorodifluoromethane. It appears, therefore, thatmore than one fluorine atom. has to be present in these derivatives inorder to cause the solvent to be selective.

The introduction of one or more fluorine atoms into propane or othersolvent will change its specific qualities for oil refining purposes,such as selectivity, suitability for deasphaltizing and ole-waxing (bydecreasing the solubility in the oil) so that it becomes more than adiluent and can be used as a selective solvent. Examples of suchfluorinated solvents are the following: trifluoropropane,difluoropropane, monofluoroethane, difiuoroethane, monofluoromethane,difiuoromethane, trifiuoromethane, and carbontetrafluoride.

The use of dichlorodifluoromethane, in accordance with our invention, isdescribed and claimed specifically in our copending application filed ofeven date herewith.

In the claims the term liquefied means that the substance referred to isused. in a liquid state, whether normally liquid or not, and theexpression predominantly fluorine containing means a halogenatedderivative of an organic substance containing one or more fluorine atomsin excess of such other halogen atoms as may be contained therein.

We claim the following as our invention:

1. A method of refining a waxy mineral oil stock comprising dissolvingthe oil in a liquefied organic fluorine compound in which the oil issoluble and at low temperatures the wax is insoluble, chilling themixture to a low temperature at which the wax separates out, removingthe separated wax, and heating the solution in a separate step to ahigher temperature to bring about phase separation, and separating thephases.

2. A method of refining a waxy mineral oil comprising dissolving the oilin a fluorine deriva tive of an aromatic hydrocarbon containng nooxygen, chlling the solution to a temperature at which the wax separatesout, removing the wax,

and extracting at an elevated temperature with a selective solvent.

3. A method of refining a mineral oil containing asphalt comprisingdissolving the oil in a fiuorinated derivative of an aromatichydrocarbon. containing no oxygen, separating out the undissclvedasphalt, chilling the solution to precipitate out wax, and removing thewax.

4. The process of refining a mineral oil comprising dissolving thesoluble constituents of the oil in a liquefied predominantly fluorinecontaining halogenated organic compound, separating the undissolvedconstituents, treating the solution with a mixture of said compound. and

a solvent selective with respect thereto to extract undesirableconstituents of the oil, and separating the phases thereby formed.

5. The process of refining a mineral oil comprising dissolving thesoluble constituents of the oil in a liquefied predominantly fluorinecontaining halogenated organc compound, separating the undissolvedconstituents, treating the solution with a mixture of said compound anda solvent miscible therewith and selective with respect to the oil toextract undesirable constituents of the oil, and separating the phasesthereby formed.

6. The process of refining a mineral oil comprising dissolving thesoluble constituents of the oil in a liquefied predominantly fluorinecontaining halogenated unsaturated hydrocarbon compound, separating theundissolved constituents, treating the solution with a mixture of saidcompound and a solvent selective with respect thereto to extractundesirable constituents of the oil, and separating the phases therebyformed.

ERNEST TERRES. ERICH SAEGEBARTH. JOSEPH MOOS.

HANS RAMSER.

